1. Field of the Invention
The present invention relates to a retainer for rolling bearing, in particular, a crown-shaped retainer of balls for use of ball bearings.
2. Related Art
The ball bearing is structured to retain a plurality of balls interposed between tracks of an inner race and an outer race by a retainer at an equal spacing in a circular direction, and as the retainer, conventionally, a crown-shaped retainer (hereinafter referred to as xe2x80x9ccrown retainerxe2x80x9d) has been often used. This crown retainer comprises a plurality of pockets 2, as shown in FIG. 5 by a sign 1, at one end for retaining a plurality of balls at an equal spacing in a circular direction, and after assembling a necessary number of balls between the tracks of the inner and outer races and disposing those balls at an equal spacing in a circular direction, the crown retainer is assembled between the inner race and the outer race while directing the pockets inward, thereby the balls are housed in each of the pockets 2 of the retainer 1.
Now, in this kind of ball bearing, in order to reduce a bearing torque (friction torque) and a friction heating, after assembling of the retainer 1, a lubricant such as a grease is applied to the pockets 2 of the retainer 1 and connecting portions 3 between the pockets 2, thereby a reduction of a frictional resistance between the retainer 1 and balls and between the balls and inner, outer races has been considered, and conventionally, the application of the lubricant to the retainer 1 has been carried out from an open end side because, in a bearing for general use, an end side opposite to the side where the retainer 1 is assembled is opened.
However, recently, in a hard disc driving apparatus, a bearing integral with an outer race (hereinafter referred to as xe2x80x9couter race integral bearing) in which the outer race and a sleeve is structured in a unitary manner has been used. This outer race integral bearing is, as an example shown in FIG. 6 by a sign 10, structured by forming two track faces 12, 13 mutually separated in an axial direction on an inner circumferential surface of the sleeve (outer race sleeve) 11 which is sleeve and at the same time functions as outer race, while preparing a stepped shaft 14, providing one track face 15 on the periphery of a large diameter 14a of the shaft 14 and another track face 16 on the periphery of an inner race 17 coupled with a small diameter portion 14b of the shaft 14 respectively and interposing plural balls 18 between the track faces 12, 13 of the outer race side and track faces 15, 16 of the inner race side. In thus outer race integral bearing, since the balls 18 are disposed in two rows, two retainers 1 become necessary, and these retainers 1 are to be assembled in the axial direction as shown in arrows A and B in the openings of both ends of the bearing 10. In this case, since both openings of the bearing 10 finished in assembling are in a state closed by the retainers 1, it becomes impossible to apply the lubricant to the pockets 2 or connecting portions 3 through the opening opposite to the side which the retainer 1 is assembled as general bearing.
Therefore, conventionally, in the outer race integral bearing 10, after assembling the retainer 1 in the openings of both ends, the lubricant has been applied in the bearing through a tiny gap existing between the periphery of the retainer 1 and the inner circumferential surface of the outer race sleeve 11. However, since this gap is quite small, it has taken a long time for applying a necessary quantity of lubricant, which has brought a low workability. Further, it has been difficult to apply the lubricant uniformly all over the retainer 1 and the track faces 12, 13, 15 and 16, eventually a variation of the bearing torque is generated or the torque itself is threatened to be increased.
The present invention has been made to solve the above conventional problems, and a first object thereof is to provide a retainer to improve a lubricant-applying workability in a closed space of a bearing, and a second object is, in addition to the above first object, to provide a retainer enabling to apply a lubricant in a stable manner to a necessary portion in the bearing, and attain an increasing of the bearing function.
According to a first invention to attain the above first object, in a crown type of rolling bearing retainer having a plurality of pockets to support rolling element at a given spacing in the circular direction, a channel in communication with one of a periphery face or an inner circumferential face or both is provided on one side opposite to the side where the pockets are provided.
In thus formed retainer, a sufficient amount of lubricant is applied effectively in the bearing through the channel.
Further, according to a second invention to attain the second object, in the above first invention, the channel is provided in a plural number by disposing these at an equal-spacing in the circular direction.
In the retainer thus formed, it is possible to apply the lubricant approximately uniformly and sufficiently in the circular direction to the necessary portions in the retainer.
In the above first and second inventions, the channel may be provided by setting openings in an annular groove formed on the end face opposite to the side provided with the pockets or in a circular groove provided on the periphery face or inner circumferential face.